Milne-like spacetimes are a class of \(k = -1\)  FLRW spacetimes which admit continuous spacetime extensions through the big bang. This extension was observed in [1]},These extensions have been noted previously in the physics literature, see e.g. [2]}. and further properties of these spacetimes were explored in [3]}. We believe that investigating the geometrical properties of the big bang extension may lead to a better understanding of cosmology.
